RICO: Gerber scientific (GSI) 1000-hz PVM. Version 1.0

This data set includes airborne measurements obtained from the NSF/NCAR C-130 aircraft during the "Rain in Cumulus Over the Ocean" (RICO) project. This data set contains 1000 hertz PVM data. The files are in netCDF format. Two hot-wire liquid water sensors and a PVM-100 laser-based liquid water sensor were mounted on the C-130 for the program. While all systems performed well, accumulation of salt on the hot-wire elements tended to increase the baseline drift in the raw output. RAF employed a loose-couple processing method to remove the excess drift. Both techniques, hot wire and PVM-100, have a tendency to underestimate the total liquid water in large drops or mixed phase clouds. The effective radius Re of the cloud droplets (XGRFF) is given by Re(um) = 30,000 x XGLWC(g/m^3)/XGSFC(cm^2/m^3). As the values of XGLWC and XGSFC approach zero the noise in the calculated values for Re will approach infinity given Re is the ratio of the two quantities. Thus to get all meaningful values of Re, a conditional statement should be applied to the ratio to avoid excessive noise. The recommended approach is to chose a limiting value of XGLWC below which no value of Re is calculated. With additional care in removing any remaining small offsets in the XGLWC and XGSFC data, the limiting value of XGLWC can be chosen as small as 0.010 g/m^3 for this data set. XGRFF was calculated with an XGLWC threshold of 0.05 and the additional condition that XGSFC>0 to avoid negative radius value.

本数据集包含美国国家科学基金会（National Science Foundation, NSF）/国家大气研究中心（National Center for Atmospheric Research, NCAR）C-130运输机在"洋面积云降雨"（Rain in Cumulus Over the Ocean，简称RICO）项目期间获取的机载观测数据。本数据集包含1000赫兹的PVM数据，文件采用netCDF格式。本次项目在C-130运输机上搭载了两支热丝式液态水传感器与一台PVM-100型激光式液态水传感器。尽管所有系统运行表现良好，但热丝传感元件表面的盐分累积会加剧原始输出的基线漂移。研究团队采用松耦合处理方法以消除该额外漂移。热丝传感器与PVM-100传感器均存在对大粒径水滴或混合相云的总液态水含量低估的问题。云滴有效半径Re（对应变量XGRFF）的计算公式为：Re(μm) = 30000 × XGLWC(g/m³)/XGSFC(cm²/m³)。由于Re为两个物理量的比值，当XGLWC与XGSFC趋近于0时，Re的计算噪声将趋于无穷大。因此为获取有意义的有效Re值，需对该比值施加条件限制以规避过度噪声。推荐的处理方案为设定XGLWC的阈值，当XGLWC低于该阈值时不计算Re值。若在处理XGLWC与XGSFC数据时进一步移除残余的微小偏移，本数据集可将XGLWC的阈值设置至低至0.010 g/m³。本次数据集生成的XGRFF参数采用了0.05 g/m³的XGLWC阈值，同时附加了XGSFC>0的条件，以避免出现负有效半径值。